1. Field of the Invention:
The present invention relates to a mold clamp apparatus for a molding machine for a synthetic resin, performing a powerful mold-clamping operation after it block a movement of a movable platen having made the mold closed.
2. Description of the Prior Art:
A blocking operation of the movement of the movable platen in this type of the mold clamp apparatus is performed with the use of a fixed platen known under the name of an end plate, or the use of a platen connected to tie bars. In a type of an apparatus in which the movable platen is blocked in its movement with the use of the fixed platen, since a mold clamp cylinder is set behind the movable platen, a construction of the movable platen is complicated to increase its weight and energy consumption for opening, closing and moving the movable platen. Further, in case that a high-speed opening/closing operation is required, such construction is disadvantageous. In contrast with this, in a type of the apparatus in which the movable platen is blocked in its movement with the use of the plate of the tie bars, since a rear mechanism for the movable platen is not required, it is possible to simplify the construction of the movable platen to reduce its weight so as to make the movable platen advantageous in case that the high-speed opening/closing operation thereof are performed. However, in this case, there is a defect in that, since the powerful mold clamping operation is conducted by pulling the tie bars with the use of the mold clamp cylinder mounted on the fixed platen, there is no means for fixing the tie bars and this results in a poor support for the movable platen.
Further, in the blocking type of the apparatus, since a pressurized hydraulic oil is fed to the mold clamp cylinder only after the movable platen is blocked in its movement, a dead time of the machine is produced between the high-speed mold closing operation and the powerful mold clamping operation. Although such dead time is a slight time interval to a time when the movable platen is blocked in its movement, it is not preferable for the mold clamp apparatus which should be operated primarily in a continous manner.